Biomechanics of hand mowing

Preface

In April 2004 Drs. Helga and Otto Fleiss (of the Steyr Institute of Vertebrae Research) were approached by the organizers of the upcoming Scythe Symposium to document the movements executed during hand mowing and analyze their effects on the body. (As a professor at the University of Graz, Dr. Fleiss’ special interest has been the strain, and the resulting chronic damage, to which the spinal column is subjected during work and sports activities).

For the purpose of the study four mowers who use somewhat different techniques were chosen and the husband and wife team made a series of photo and video sequences. Their conclusions to date, superbly presented by Dr. Fleiss during the Symposium, confirmed my long-standing conviction that, at its best, wielding a scythe causes no stress to the spine and can indeed be considered body therapy.

At the end of the Festival week they filmed still more technique variations (including a member of the Austrian national mowing team) and eventually a comprehensive report written by the Drs. themselves will be available in print.

As one of the initial group I had been asked, still in April 2004, to write a short essay which would explain the reasons behind my rather unorthodox mowing style. Now somewhat expanded, it is posted here not as a substitute for a professional analysis of the movement but rather a description by a farmer of what he does and why he does it.

Photo by Dr. Otto FleissClick image for a larger version

-Peter Vido, January 3, 2005

There are numerous references in prose, poetry and songs from many cultures indicating that a good scythe fits in the category of hand tools the use of which can be physically and mentally therapeutic. Indeed, hand mowing was frequently likened to dancing.

To function as physiotherapy it must, however, be performed so as to keep the body in the most comfortable posture ( and, ideally, it should also make the best use of the person’s available energy).

Some traditional mowing styles accomplished this; many did not. Certain snath/blade combinations, for instance, dictated more leaning forward than is healthy for the spine and, to various degrees of intensity, the scythe has been powered predominantly by one arm.

The country folk, with their strong constitution, apparently accepted much of that as inevitable; perhaps this was because, relative to other kinds of farm work, using the scythe was easy. (One old Austrian even told me that “a man should be able to rest himself while mowing”.)

Though as a farmer I started to use this wonderful tool primarily for practical purposes, its potential as a “medicine” took my attention from the beginning. But, with an accident-damaged right shoulder and right wrist, I could not mow in the conventional manner for long at a time. Obtaining a left-handed scythe may have been the thing to do, though back then I did not know any existed.

CONSIDERING ERGONOMY

I became concerned with three issues to which many serious hand tool users surely have given much thought:

that the tool is first designed and later maintained (adjustments, sharpness etc.) so it functions as efficiently as possible;

that the user is applying his/her body’s motive power also in the most efficient manner;

related to both of the above and especially in instances where the tool is used for long periods, the user should be comfortable.

The more I mowed with these objectives in mind, the more it seemed that, from the perspective of ergonomy, the “conventional” technique could be improved. For instance, by applying the strength of the legs, i.e. propelling the blade partially by the shifting of body weight from side to side, the demand on the arms is significantly reduced and they do not tire nearly as fast. The shoulders and neck can also remain more relaxedand the movement feels more “balanced”.

The mowing technique described below evolved gradually as I attempted to:

distribute the demand for strength as equally as possible over my body

optimally synchronize the movement with the rate at which I like to breathe.

THE MOVEMENT ILLUSTRATED

What I refer to as “one complete movement” or just “movement” consists of two phases: the slicing stroke(blade moving forward) and the return stroke (blade moving back to the starting position).
As the movement begins (Photo #1) most of the girl’s weight is on the right leg, which at that point is also bent. She is leaning slightly to the right with the blade resting on the ground.

Photo#1

As the blade moves forward (Photos #2 and #3) the right leg gradually straightens and the left leg begins to flex. The torso is turning, following the “path of the blade”, with the abdominal muscles aiding the twisting movement.

Photo#2

Photo#3

At the point when the slicing stroke, i.e. the first phase, is finished (Photo #4) the weight is on the left leg which is now bent. The right foot, relieved of weight, then moves (shuffles) forward a distance equal to one stroke’s advancement into the stand of grass, i.e.10-20 cm. In easy cutting, with a sharp blade 90 cm. or longer, the advance may be 30+ cm.Note that the girl’s sideways lean in either direction (Photos 1-4) does not exceed the comfort zone of the knee joints.

Photo#4

In Photo 5 she just finished the return stroke and her left heel is slightly elevated as she takes a step forward. Her neck, back and lower leg all have nearly the same slope. This is a relatively healthy posture which does not strain the spine (and is very similar to one of the basic stances in Tai-chi practice).

Photo#5

To a small degree, her body is supported at all times by the tool’s continuous contact with the ground, because the blade remains touching the surface during both phases of the movement. On the return stroke only its heel is lifted – to ease the friction and/or to help release any tangled vegetation – but drops down before the blade begins to move forward again.

Lifting the whole blade off the surface on the back stroke, and consequently having it slightly elevated just prior to the next slice, is the norm in some traditional mowing styles. The logic, I assume, is that it creates more velocity for the cutting. While this may be true, the energy expended outweighs the benefit if therapeutic movement is the mower’s goal. An hour of field mowing entails 1200 to 1500 strokes and the average scythe (blade/snath unit) weighs approximately 3.5 to 4 pounds (1.5 to 1.8 kg.)–which translates into lifting, needlessly, more than two tons. Personally I feel that the “body weight shift” is sufficient as a propelling force and from the perspective of ergonomy a better one.

In addition, each half of the “complete movement” involves a partial body twist, which has an effect similar to compressing a coil spring: a motive force of kinetic energy is built up and stored momentarily in muscles and tendons. The move in the opposite direction then makes efficient use of it in propelling the blade without unhealthy strain on the body. That twisting alone is an excellent way of limbering up the spine and adds to the overall health benefit of mowing.

Occasionally people ask me if the “sideways weight shifting” does not strain the knees, or comment that because they have “bad knees” they could not use them to “push like that”.

Actually, I push very little with my knees. Yes, they do need to flex and straighten, but beyond that, they are more or less just “along for the ride”. There is no lateral strain because I keep them over the toes; that is, sighting down my thigh and across the centre of my kneecap an imaginary line would meet the toes. Also, the above discussed twisting takes place primarily in the upper body, i.e. from the waist up. In the knees it is minimal.

So what does power the shift? The simple answer is: the lower and upper leg muscles (along with, of course, the extensor tendons).

There is also another kind of explanation.

The shift begins in the mind. Then comes the foot; always the one which, at that moment when the propelling force is needed, is placed firmly on the ground. (The other foot at that very point just finished its step forward.) Although low on muscle mass, the feet can act as conductors of an “energy current”. If my mind is focused enough (some days it isn’t) I can “breathe” this energy in through the soles of my feet and help power the sideways shift. When my mind is “elsewhere”, I don’t make use of that freely offered life force and need to rely solely on the muscles of my body. The difference is noticeable — I tire sooner and miss some of the “bliss”.

As for the initial knee-related question—I’m convinced that the mowing style described here functions as physiotherapy rather than stress to my knees. You see, I have had to live with “bad knees” for many years. For more details read Note 1 (see bottom of page).

THE IMPORTANCE OF BREATHING

As we engage in any strenuous rhythmic activity it is quite natural to time one’s breathing in harmony with the movements. Likewise, the girl in the photos 1 to 3 (while pushing) is exhaling, and on the return stroke (Photo 4) she inhales.

This is rather elemental, and every mower doing a long rhythmic stroke, regardless of style, would synchronize the exhalations with the blade’s forward movement.

But partly incorporated into the mowing style discussed here is an additional concept, one which Oriental medicine has long emphasized–that the slower and deeper one’s breathing, the greater will be the therapeutic effect. The given here is that breath, besides providing us with oxygen, is also the carrier of “chi” (see Note 2 at bottom of page).

During intermittent periods of my last 35 years I’ve practiced various health-oriented techniques “imported” from the Far East and have no doubt as to their virtue. Analogies can be drawn between some of these disciplines (especially Tai-chi) and the art of mowing; the above discussed manner of powering the body shift is but one of them.

Yet moving the scythe through a stand of grass as slowly as one does while practicing the classical Tai-chi form would not serve its intended purpose. The main reason is simply because the physics of efficiently severing plant stems dictates some minimum speed below which the scythe blade edge does not perform well.

Nevertheless, I’ve attempted to coalesce grass cutting with meditation, and to that end, slowing down the breathing rate was one of my initial concerns.

The traditional swaths vary between 1.5m. and 2.2m. and the mowers take 0.9 seconds or less for the slicing stroke. Having, by means of the sideways shift, increased the mowed width to 2.8m.-2.9m., I can breathe somewhat deeper. Depending on cutting conditions, I take 1.1 to 1.3 seconds to exhale (slicing stroke) and 1.3 to 1.5 seconds to inhale (return stroke). This feels personally comfortable, considering that I am out there to cut grass and not merely meditate!

“All that Glitters is not Gold”

One British scythe-promoting writer, who saw my mowing technique during the Scythe Festival in Austria, in a magazine article, referred to it as “extremely efficient”. I felt compelled to correct him, suggesting that “energy conserving” or “easy on the body” would be more fitting.

Thus I feel that some qualifications of the previously discussed guidelines may be in order.

Firstly, cutting an extra wide swath is not always advantageous or desirable or, for that matter, extremely efficient. It all depends on one’s parameters of efficiency. The movement as discussed here may not be readily appreciated if the goal is strictly to get the grass cut and the mower has energy to spare. For instance, a strong man cutting a 2m. swath and powering the scythe mostly by the upper body can, under certain circumstances (see Note 3; scroll to end of page), cover as much (or more) surface in a given period as I do by my 2.9m wide movement, but he will have worked harder for his grass.

I’m certain that, even if we discount the therapeutic effect, neither I nor my wife or children could cut as much as we do if we used any of the traditional mowing styles I am familiar with. (We would all simply run out of strength far sooner.) Secondly, this wide movement is wholly unsuitable for the short-duration mowing competitions where speed, rather than energy conserving technique, plays such a vital role.

FITTING THE SNATH

Our friend Tony Beeler (a Swiss farmer and at one time his country’s mowing champion) is fond of saying, “A good mower can mow with any scythe and a poor one can’t mow with any”.

In a way he is right; I’ve seen him demonstrate that by mowing exceedingly well with snaths ranging from several sizes too long for him to one fitted for a 10-year-old boy. But few people are like Tony…and for best results the snath should have specific measurements determined by the person’s size as well as the nature of the terrain to be mowed.

In addition, a serious mower using the scythe for a variety of tasks would be far better off with at least two purpose-specific sizes of this tool. For lack of other generally accepted terms in this regard I refer to them asfield scythe and trimming scythe.

The field scythe, with a longer blade and a longer snath, is better for work in areas which present no restrictions to the width of swath (which, of course, could also be a spacious orchard or a lawn). For the style of movement discussed above, with its deeper and more meditative breathing, this is the preferred version.

The trimming scythe is more suitable when obstacles or the nature of the terrain limit mowing width and dictate alternate or continually changing stroke patterns. With respect to the other, it should have a shorter blade and shorter snath. I would choose a snath of yet different measurements for extensive mowing on a very steep slope, for example, but the above are the two “basic models”.

The pivotal point of reference in my formula of measuring a tailor-sized snath is the hip joint upon which the torso rotates during mowing. I will call the distance between this point on the body and the ground as “A” (Diagram 1):

All variations with regard to an individual’s body proportions notwithstanding, I believe that the right hand grip (i.e. the lower one) of a trimming snath should reach to the person’s hip joint when the snath, with the blade mounted, is stood alongside the mower as pictured in Diagram 1 – and at least 5 cm above that point for a field snath. (The measuring is done in the footwear used for mowing; this can make as much as several cm. difference.)

Now (in Diagram 2) we can refer to the distance between the snath’s lower grip and the end of the unit as “A1” for trimming work and “A2” for field work. The distance between the grips we can call “B” and “B2” respectively. B1 should be the distance from the mower’s elbow to the outermost fingertip of the outstretched hand, also called a “cubit”. B2 should be 5-10cm longer than that.

There are two details which, incorporated into the snath design, result in a more ergonomic tool because they help me work in a more relaxed manner:

extra wood near the top end of the snath (in order to offset the weight of the blade and so give the whole tool a more balanced feel;
the shape of the grips and the angle at which they are attached to the snath.

Note 1:

I had dislocated my left knee 18 years ago (in a wrestling match) and the right one (in a forest-work-related accident) a few years later. Since then low level chronic pain has been my daily companion.

Wearing tight elastic bandages during, for instance, work in the woods helped but did not prevent the joint’s tendency to unexpectedly slip out of place – sometimes just a little, at other times more.

I believe that a marked, albeit gradual improvement began to take place when I started to use the scythe more seriously, performing this “wide” movement. To me the saying “Time heals all wounds” does not quite account for the change. For one thing, it is more noticeable each year shortly after our mowing season begins. (I’m out there by mid May, a full month before any sane farmer in this area would consider cutting any grass.) In part this could be attributed to the psychosomatic effect– the birds are singing, dandelions blooming and I’m barefoot again. But I’ve put away my shoes for the last 30 frost-free seasons of my life and each year birds return and flowers bloom…Generally, younger bodies heal faster. Why the improvement to my knees now (when I’m almost 55) and not 10 years or so earlier?

Another piece of evidence: A few months before that first knee injury I had started to train at a local Kung Fu school (something I had enjoyed during my student years). That wrestling match was part of a martial arts demo day. Periodically I had tried to return – but my knees couldn’t take even one class. So for a long time I gave up on the idea. Last year, with my daughters in the same school, I tried again– and it worked! Not quite like 35 years ago but enough to have a little fun and stay limber…

Note 2:

Variously translated into English, though usually denoting something like “vital energy essence”, chi has not yet been isolated in a test tube and thoroughly analyzed. Just as well, or some mad scientist would surely attempt to genetically modify and/or patent it and claim that doing so is “in the best interest of humanity”…

Note 3:

The relationship between the width of the swath, the forward advance at a stroke, and the blade’s “hafting angle” are too complex to cover here at any length, but as a rule, it is easier to take a deeper slice (advance further into the stand of grass) when cutting a narrower swath. So if, with a 90cm blade, I move forward 20cm with each 290cm stroke, I could just as easily move 25cm forward with each 220cm stroke, thus covering nearly the same surface. I could also do it in less time, but would work harder with my arms.

I prefer a relatively narrow “hafting angle” because a blade so adjusted simply pulls easier.

Austrian mowers usually have their scythes hafted “in circle” (meaning that both the point and the beard of the blade are the same distance from the upper grip) so they can take a larger “bite”. One of them, cutting a 220cm swath with a 90cm blade, could move ahead 30cm at a stroke, and because their back and forth movement is 20-30% faster, cover more surface than I and in less time.